Thursday (Feb. 29) is "leap day," an artifact that dates back to the year 46 B.C. Find out how this calendar oddity came to be.

If the year can be evenly divided by 100, it is not a leap year unless the year is also evenly divisible by 400, according to mathisfun.com. For example, 2000 and 2400 are leap years, but 1800 ...

This brought the average length of the Gregorian year to 365.2425 days, off by just 26 seconds compared to a solar year. While under the Julian calendar, a day shift accumulated every 129 years ...

In honor of Leap Day, this read is for the history nerds. Ever wonder how America caught our calendar up with the rest of the world? In September 1752, we skipped over 11 days.

There are a number of different calendars used around the world today, including the Gregorian calendar (in which the current year is 2025) and the traditional Chinese calendar (in which the ...

In the Julian calendar, the new year began on March 25. So March 24, 1701 would be followed directly by March 25, 1702. The Gregorian calendar, as we know today, begins on January 1. ...